The present invention relates to a refrigerating apparatus with reduced restarting load and more specifically to a refrigerator equipped with an open-close valve which rapidly closes a circuit to prevent condensed refrigerant from entering into the evaporator when the rotary compressor is stopped.
With this refrigerating apparatus, when the compressor is stopped, the pressure difference of the refrigerant or coolant before and after the compressor is balanced to block the condensed refrigerant flowing back into the evaporator, while at the same time maintaining high pressure of condensed refrigerant of the condenser so as to reduce the restarting load and thereby improve power efficiency.
It has been a common practice to provide a solenoid valve between the condenser and capillary tube with the solenoid valve opened and closed by a compressor operation signal when the compressor is started and stopped respectively. With refrigerators that are used continuously for many hours, however, it is desired not to use the solenoid valve because of a large installation space though its power consumption is small. The noise of the solenoid valve also has frequently been pointed out.
Recently, a technique has been developed to use a pressure valve in place of the solenoid valve.
FIG. 1 illustrates a refrigerating apparatus employing such a pressure valve. The apparatus consists of a rotary compressor A, a condenser B, a capillary tube C as a pressure reducing mechanism or a throttle, and an evaporator D, all these connected in series by a pipe E. A pressure differential valve V.sub.1 is provided between the condenser B and the pressure reducing mechanism or throttle C with a pressure introducing tube F led from the valve V.sub.1 to the suction side of the rotary compressor. A check valve V.sub.2 is installed between the evaporator D and the rotary compressor A.
The detailed structure of the pressure differential valve V.sub.1 is shown in FIG. 2. The valve body 1 has a primary port 2 and a secondary port 3 and also has a valve seat 4 between these ports with which a ball valve 5 is adapted to come into or out of contact. At the top of the valve body 1 are mounted upper and lower covers 6, 7 which clamp a diaphragm 8 at its periphery. Formed in the upper cover 6 is a pressure chamber with which the pressure introducing tube F communicates. A spring 10 is installed between the upper cover 6 and one side of the diaphragm 8 through a retainer 9. A valve rod 11 is abutted against the other side of the diaphragm 8 and a spring 12 is installed between the valve rod 11 and the valve body 1. A pipe E.sub.1 leading from the condenser B is connected to the primary port 2 and another pipe E2 coming from the capillary tube C is connected to the secondary port 3.
Another example of the refrigerating apparatus using the pressure valve is shown in FIG. 3, in which a rotary compressor A, a condenser B, a capillary tube C and an evaporator D are connected in series by a pipe E. A pressure differential valve V.sub.1 ' is installed between the capillary tube C and the evaporator D. A pressure introducing tube F for the valve is connected to the suction side of the rotary compressor A. A check valve is installed between the evaporator D and rotary compressor A.
As shown in FIG. 4, the body 13 of the pressure differential valve V.sub.1 ' has a primary port 14 and a secondary port 15, and also has a seat 16 between the ports with which a ball valve 17 provided on the secondary port side is adapted to come into or out of contact. Mounted on top of the valve body 13 are upper and lower covers 18, 19 which hold a diaphragm 20. Formed in the upper cover 18 is a pressure chamber with which the pressure introducing tube F is communicated. A valve rod 21 is abutted against the underside of the diaphragm 20. A spring 22 is installed between the valve rod 21 and the lower cover 19. A pipe E3 from the capillary tube C is connected to the primary port 14 and another pipe E4 leading to the evaporator D is connected to the secondary port 15.
In the first example of the refrigerating apparatus, a high pressure of the condenser B is applied to the primary port of the pressure differential valve V.sub.1, so that a significant amount of leak and time is necessary to obtain a sufficient force to close the valve. During this period high pressure liquid may flow into the evaporator impairing its function. The spring used to resist that high pressure must have a large spring constant. Therefore, if the pressure difference is small, the valve disk will not operate easily. Also since the high pressure varies in a wide range of 2 to 15 kg/cm.sup.2 G, it is difficult to set the correct valve operation range. When the spring load is large the valve closing action is quick. However, when the ambient temperature is low the condenser pressure will not increase to a level high enough to open the valve, with the result that the refrigerating apparatus cannot be operated. On the other hand, when the spring load is small and if the lead from the compressor is small when the refrigerating apparatus is stopped, the pressure in the pressure introducing tube F will not increase sifficiently rapidly so that the valve will not close letting the high pressure liquid flow into the evaporator.
The second example of the refrigerating apparatus makes use of the fact that the pressure of the evaporator does not change greatly when the refrigerating apparatus is stopped or started. When the rotary compressor is stopped, the pressure differential valve is operated by the pressure difference between the leak from the rotary compressor and the evaporator pressure in order to quickly block the high pressure liquid flowing into the evaporator.
However, the refrigerating apparatus in which the pressure differential valve is installled downstream of the pressure reducing mechanism or a trottle C consisting of a capillary tube has the following drawbacks. With the refrigerator, it is necessary to install the pressure differential valve inside the refrigerator box to prevent formation of dew and frost as well as deteriorated freezing efficiency. This makes small the space inside the box and also makes the assembly work difficult. With the air conditioner, the rotary compressor and condenser are installed outside the room and the pressure reducing mechanism and evaporator installed inside the room. This requires two pipes for connecting the indoor and outdoor equipment and also a third pipe, a pressure introducing tube F which connects the pressure differential valve V.sub.1 ', interposed between the pressure reducing mechanism C and evaporator D, to the suction side of the rotary compressor A.